Synaptophysin immunostaining in C57BL6/J and iNOS-/- mice, one week after unilateral axotomy. Note that one week after lesioning, there was a stronger decrease in labeling especially in the areas surrounding the motoneurons. This decrease was more intense in iNOS-/- mice (D) than in C57BL6/J mice (B). (A and C) Unlesioned side of C57BL6/J and iNOS-/- mice, respectively. The dashed circle indicates the motor nucleus containing the alpha motoneurons. (E) Graph representing quantification of the integrated density of pixels in the neuropil adjacent to large motoneurons. * = p < 0.05 (Student t test). Scale bar = 50 μm.